2,987 research outputs found
Open-Loop Spatial Multiplexing and Diversity Communications in Ad Hoc Networks
This paper investigates the performance of open-loop multi-antenna
point-to-point links in ad hoc networks with slotted ALOHA medium access
control (MAC). We consider spatial multiplexing transmission with linear
maximum ratio combining and zero forcing receivers, as well as orthogonal space
time block coded transmission. New closed-form expressions are derived for the
outage probability, throughput and transmission capacity. Our results
demonstrate that both the best performing scheme and the optimum number of
transmit antennas depend on different network parameters, such as the node
intensity and the signal-to-interference-and-noise ratio operating value. We
then compare the performance to a network consisting of single-antenna devices
and an idealized fully centrally coordinated MAC. These results show that
multi-antenna schemes with a simple decentralized slotted ALOHA MAC can
outperform even idealized single-antenna networks in various practical
scenarios.Comment: 51 pages, 19 figures, submitted to IEEE Transactions on Information
Theor
Markov Models of Telephone Speech Dialogues
Analogue speech signals are the most natural form of communication among humans. The contemporary methods adopted for the analysis of voice transmission by packet switching were designed mainly with respect to a Poisson stream of input packets, for which the probability of an active packet on each input port of the router is a constant value in time. An assumption that is not always valid, since the formation of speech packets during a dialogue is a non-stationary process, in which case mathematical modeling becomes an effective method of analysis, through which necessary estimates of a network node being designed for packet transmission of speech may be obtained. This paper presents the result of analysis of mathematical models of Markov chain based speech packet sources vis-Ã -vis the peculiarities of telephone dialogue models. The derived models can be employed in the design and development of methods of statistical multiplexing of packet switching network nodes
Modeling Profit of Sliced 5G Networks for Advanced Network Resource Management and Slice Implementation
The core innovation in future 5G cellular networksnetwork slicing, aims at
providing a flexible and efficient framework of network organization and
resource management. The revolutionary network architecture based on slices,
makes most of the current network cost models obsolete, as they estimate the
expenditures in a static manner. In this paper, a novel methodology is
proposed, in which a value chain in sliced networks is presented. Based on the
proposed value chain, the profits generated by different slices are analyzed,
and the task of network resource management is modeled as a multiobjective
optimization problem. Setting strong assumptions, this optimization problem is
analyzed starting from a simple ideal scenario. By removing the assumptions
step-by-step, realistic but complex use cases are approached. Through this
progressive analysis, technical challenges in slice implementation and network
optimization are investigated under different scenarios. For each challenge,
some potentially available solutions are suggested, and likely applications are
also discussed
Transmission Capacity of Ad-hoc Networks with Multiple Antennas using Transmit Stream Adaptation and Interference Cancelation
The transmission capacity of an ad-hoc network is the maximum density of
active transmitters per unit area, given an outage constraint at each receiver
for a fixed rate of transmission. Assuming that the transmitter locations are
distributed as a Poisson point process, this paper derives upper and lower
bounds on the transmission capacity of an ad-hoc network when each node is
equipped with multiple antennas. The transmitter either uses eigen multi-mode
beamforming or a subset of its antennas to transmit multiple data streams,
while the receiver uses partial zero forcing to cancel certain interferers
using some of its spatial receive degrees of freedom (SRDOF). The receiver
either cancels the nearest interferers or those interferers that maximize the
post-cancelation signal-to-interference ratio. Using the obtained bounds, the
optimal number of data streams to transmit, and the optimal SRDOF to use for
interference cancelation are derived that provide the best scaling of the
transmission capacity with the number of antennas. With beamforming, single
data stream transmission together with using all but one SRDOF for interference
cancelation is optimal, while without beamforming, single data stream
transmission together with using a fraction of the total SRDOF for interference
cancelation is optimal.Comment: Accepted for publication in IEEE Transactions on Information Theory,
Sept 201
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